Don't call me weird for this:
Zen Music for Relaxation
Yes, it's Chinese music, but I needed something to help me concentrate more on my portfolio. It's actually pretty good.
Actually, Asian music is about the only type of music I'm for sure I'll listen too. English Rock, maybe; Rap, never in my life (I'm black, so don't call me racist. I just hate the beats and the subject matter); Country, more likely to listen to it than rap. The only other music I'll listen to is Gospel, but only because I have to drive in my mom or dad's car.
I might give Celtic, Reggae, Latin, Native American and African music a try just to see how each culture implements music.